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Rinaldi G, Paz Meseguer C, Cantacessi C, Cortés A. Form and Function in the Digenea, with an Emphasis on Host-Parasite and Parasite-Bacteria Interactions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1454:3-45. [PMID: 39008262 DOI: 10.1007/978-3-031-60121-7_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
This review covers the general aspects of the anatomy and physiology of the major body systems in digenetic trematodes, with an emphasis on new knowledge of the area acquired since the publication of the second edition of this book in 2019. In addition to reporting on key recent advances in the morphology and physiology of tegumentary, sensory, neuromuscular, digestive, excretory, and reproductive systems, and their roles in host-parasite interactions, this edition includes a section discussing the known and putative roles of bacteria in digenean biology and physiology. Furthermore, a brief discussion of current trends in the development of novel treatment and control strategies based on a better understanding of the trematode body systems and associated bacteria is provided.
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Affiliation(s)
- Gabriel Rinaldi
- Department of Life Sciences, Edward Llwyd Building, Aberystwyth University, Aberystwyth, UK
| | - Carla Paz Meseguer
- Department of Pharmacy and Pharmaceutical Technology and Parasitology, School of Pharmacy and Food Sciences, Universitat de València, Valencia, Spain
| | - Cinzia Cantacessi
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Alba Cortés
- Department of Pharmacy and Pharmaceutical Technology and Parasitology, School of Pharmacy and Food Sciences, Universitat de València, Valencia, Spain.
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Taylor SD. Potomac Horse Fever. Vet Clin North Am Equine Pract 2023; 39:37-45. [PMID: 36737286 DOI: 10.1016/j.cveq.2022.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Potomac horse fever (PHF) is a common cause of equine colitis in endemic areas. Until recently, the only causative agent known to cause PHF was Neorickettsia risticii. However, N. findlayensis has been isolated from affected horses. Horses typically become infected upon ingestion of Neorickettsia spp.-infected trematodes within aquatic insects. The most common clinical signs include diarrhea, fever, anorexia, lethargy and colic. The diagnostic test of choice for PHF is PCR of blood and feces. Tetracyclines remain an effective treatment. Supportive care, including fluid therapy, colloid administration, NSAID and anti-endotoxin medication, and digital cryotherapy, is also necessary in some cases.
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Affiliation(s)
- Sandra D Taylor
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, 625 Harrison Street, West Lafayette, IN 47907, USA.
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Buddenborg SK, Bu L, Zhang SM, Schilkey FD, Mkoji GM, Loker ES. Transcriptomic responses of Biomphalaria pfeifferi to Schistosoma mansoni: Investigation of a neglected African snail that supports more S. mansoni transmission than any other snail species. PLoS Negl Trop Dis 2017; 11:e0005984. [PMID: 29045404 PMCID: PMC5685644 DOI: 10.1371/journal.pntd.0005984] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 11/14/2017] [Accepted: 09/20/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Biomphalaria pfeifferi is highly compatible with the widespread human-infecting blood fluke Schistosoma mansoni and transmits more cases of this parasite to people than any other snail species. For these reasons, B. pfeifferi is the world's most important vector snail for S. mansoni, yet we know relatively little at the molecular level regarding the interactions between B. pfeifferi and S. mansoni from early-stage sporocyst transformation to the development of cercariae. METHODOLOGY/PRINCIPAL FINDINGS We sought to capture a portrait of the response of B. pfeifferi to S. mansoni as it occurs in nature by undertaking Illumina dual RNA-Seq on uninfected control B. pfeifferi and three intramolluscan developmental stages (1- and 3-days post infection and patent, cercariae-producing infections) using field-derived west Kenyan specimens. A high-quality, well-annotated de novo B. pfeifferi transcriptome was assembled from over a half billion non-S. mansoni paired-end reads. Reads associated with potential symbionts were noted. Some infected snails yielded fewer normalized S. mansoni reads and showed different patterns of transcriptional response than others, an indication that the ability of field-derived snails to support and respond to infection is variable. Alterations in transcripts associated with reproduction were noted, including for the oviposition-related hormone ovipostatin and enzymes involved in metabolism of bioactive amines like dopamine or serotonin. Shedding snails exhibited responses consistent with the need for tissue repair. Both generalized stress and immune factors immune factors (VIgLs, PGRPs, BGBPs, complement C1q-like, chitinases) exhibited complex transcriptional responses in this compatible host-parasite system. SIGNIFICANCE This study provides for the first time a large sequence data set to help in interpreting the important vector role of the neglected snail B. pfeifferi in transmission of S. mansoni, including with an emphasis on more natural, field-derived specimens. We have identified B. pfeifferi targets particularly responsive during infection that enable further dissection of the functional role of these candidate molecules.
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Affiliation(s)
- Sarah K. Buddenborg
- Department of Biology, Center for Evolutionary and Theoretical Immunology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Lijing Bu
- Department of Biology, Center for Evolutionary and Theoretical Immunology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Si-Ming Zhang
- Department of Biology, Center for Evolutionary and Theoretical Immunology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Faye D. Schilkey
- National Center for Genome Resources, Santa Fe, New Mexico, United States of America
| | - Gerald M. Mkoji
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, KEN
| | - Eric S. Loker
- Department of Biology, Center for Evolutionary and Theoretical Immunology, University of New Mexico, Albuquerque, New Mexico, United States of America
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Costa R, Vitari G, Silva C, Peckle M, Pires M, Brandolini S, Pinheiro J, Massard C, Santos H. Molecular investigation of Neorickettsia risticii in trematodes and snails in a region with serological evidence of this agent in horses, state of Rio de Janeiro. ARQ BRAS MED VET ZOO 2016. [DOI: 10.1590/1678-4162-8804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
ABSTRACT In Brazil, some studies have indicated that Neorickettsia risticii circulates in horses, but it is unclear which are the possible intermediate vectors of this bacterium in the country. The aim of this study was to use molecular techniques in order to analyze the presence of N. risticii in snails and larval stages of trematodes in farms in a region with a history of seroreactive horses towards this bacterium, in Rio de Janeiro, Brazil. Convenience sampling was used in the studied region. The collected snails were exposed to incandescent light (60W) for 2-4 hours in order to investigate trematodes in larval forms. Deoxyribonucleic acid (DNA) was extracted from snail tissue and trematode. Real-time PCR (qPCR) technique was used to investigate the presence of a 16S rRNA gene fragment of N. risticii. Snail specimens (n=410) were collected from 11 horse-breeding farms, and the following species were identified: Melanoides tuberculata, Pomacea sp., Biomphalaria tenagophila, Physa acuta, Drepanotrema anatinum and Biomphalaria straminea. Only 3.17% (n=13/410) of the collected snails were infected by trematodes. The cercariae obtained from these snails were classified as Megalourous cercariae, Pleurolophocercus cercariae and Furcocercous cercariae. There was no amplification of the target DNA of N. risticii in the snail and trematode samples tested by qPCR. Based on these data, the transmission of N. risticii by trematodes using these snail species in this region does not appear to occur or occurs at very low rates. Thus, further studies are needed in order to clarify which species of invertebrate hosts are infected by this bacterium and potentially participate in the transmission chain of equine neorickettsiosis in the state of Rio de Janeiro, Brazil.
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Affiliation(s)
- R.L. Costa
- Universidade Federal Rural do Rio de Janeiro, Brazil
| | - G.L.V. Vitari
- Universidade Federal Rural do Rio de Janeiro, Brazil
| | - C.B. Silva
- Universidade Federal Rural do Rio de Janeiro, Brazil
| | - M.P. Peckle
- Universidade Federal Rural do Rio de Janeiro, Brazil
| | - M.S. Pires
- Universidade Federal Rural do Rio de Janeiro, Brazil
| | | | - J. Pinheiro
- Universidade Federal Rural do Rio de Janeiro, Brazil
| | - C.L. Massard
- Universidade Federal Rural do Rio de Janeiro, Brazil
| | - H.A. Santos
- Universidade Federal Rural do Rio de Janeiro, Brazil
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An Ecotype of Neorickettsia risticii Causing Potomac Horse Fever in Canada. Appl Environ Microbiol 2016; 82:6030-6. [PMID: 27474720 DOI: 10.1128/aem.01366-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 07/27/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Neorickettsia (formerly Ehrlichia) risticii is an obligatory intracellular bacterium of digenetic trematodes. When a horse accidentally ingests aquatic insects containing encysted trematodes infected with N. risticii, the bacterium is transmitted from trematodes to horse cells and causes an acute and often fatal disease called Potomac horse fever (PHF). Since the discovery of N. risticii in the United States in 1984, using immunofluorescence and PCR assays, PHF has been increasingly recognized throughout North America and South America. However, so far, there exist only a few stable N. risticii culture isolates, all of which are from horses within the United States, and the strain diversity and environmental spreading and distribution of pathogenic N. risticii strains remain poorly understood. This paper reports the isolation of N. risticii from the blood of a horse with acute PHF in Ontario, Canada. Intracellular N. risticii colonies were detected in P388D1 cells after 47 days of culturing and 8 days after the addition of rapamycin. Molecular phylogenetic analysis based on amino acid sequences of major surface proteins P51 and Ssa1 showed that this isolate is distinct from any previously sequenced strains but closely related to midwestern U.S. strains. This is the first Canadian strain cultured, and a new method was developed to reactivate dormant N. risticii to improve culture isolation. IMPORTANCE Neorickettsia risticii is an environmental bacterium that lives inside flukes that are parasitic to aquatic snails, insects, and bats. When a horse accidentally ingests insects harboring flukes infected with N. risticii, the bacterium is transmitted to the horse and causes an acute and often fatal disease called Potomac horse fever. Although the disease has been increasingly recognized throughout North and South America, N. risticii has not been cultured outside the United States. This paper reports the first Canadian strain cultured and a new method to effectively culture isolate N. risticii from the horse blood sample. Molecular analysis showed that the genotype of this Canadian strain is distinct from previously sequenced strains but closely related to midwestern U.S. strains. Culture isolation of N. risticii strains would confirm the geographic presence of pathogenic N. risticii, help elucidate N. risticii strain diversity and environmental spreading and distribution, and improve diagnosis and development of vaccines for this dreadful disease.
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Greiman SE, Tkach VV, Vaughan JA. Transmission rates of the bacterial endosymbiont, Neorickettsia risticii, during the asexual reproduction phase of its digenean host, Plagiorchis elegans, within naturally infected lymnaeid snails. Parasit Vectors 2013; 6:303. [PMID: 24383453 PMCID: PMC3924192 DOI: 10.1186/1756-3305-6-303] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 09/30/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Neorickettsia are obligate intracellular bacterial endosymbionts of digenean parasites present in all lifestages of digeneans. Quantitative information on the transmission of neorickettsial endosymbionts throughout the complex life cycles of digeneans is lacking. This study quantified the transmission of Neorickettsia during the asexual reproductive phase of a digenean parasite, Plagiorchis elegans, developing within naturally parasitized lymnaeid pond snails. METHODS Lymnaea stagnalis snails were collected from 3 ponds in Nelson County, North Dakota and screened for the presence of digenean cercariae. Cercariae were identified to species by PCR and sequencing of the 28S rRNA gene. Neorickettsia infections were initially detected using nested PCR and sequencing of a partial 16S rRNA gene of pooled cercariae shed from each parasitized snail. Fifty to 100 single cercariae or sporocysts were isolated from each of six parasitized snails and tested for the presence of Neorickettsia using nested PCR to estimate the efficiency at which Neorickettsia were transmitted to cercariae during asexual development of the digenean. RESULTS A total of 616 L. stagnalis were collected and 240 (39%) shed digenean cercariae. Of these, 18 (8%) were Neorickettsia-positive. Six Neorickettsia infections were selected to determine the transmission efficiency of Neorickettsia from mother to daughter sporocyst and from daughter sporocyst to cercaria. The prevalence of neorickettsiae in cercariae varied from 11 to 91%. The prevalence of neorickettsiae in sporocysts from one snail was 100%. CONCLUSION Prevalence of Neorickettsia infection in cercariae of Plagiorchis elegans was variable and never reached 100%. Reasons for this are speculative, however, the low prevalence of Neorickettsia observed in some of our samples (11 to 52%) differs from the high prevalence of other, related bacterial endosymbionts, e.g. Wolbachia in Wolbachia-dependent filariid nematodes, where the prevalence among progeny is universally 100%. This suggests that, unlike the Wolbachia-filaria relationship, the Neorickettsia-digenean relationship is not obligatory mutualism. Our study represents the first quantitative estimate of the Neorickettsia transmission through the asexual phase of the digenean life cycle.
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Affiliation(s)
- Stephen E Greiman
- Department of Biology, University of North Dakota, 10 Cornell St,, Grand Forks, North Dakota 58202, USA.
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Bertin F, Reising A, Slovis N, Constable P, Taylor S. Clinical and Clinicopathological Factors Associated with Survival in 44 Horses with Equine Neorickettsiosis (Potomac Horse Fever). J Vet Intern Med 2013; 27:1528-34. [PMID: 24118378 DOI: 10.1111/jvim.12209] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 06/01/2013] [Accepted: 08/21/2013] [Indexed: 12/01/2022] Open
Affiliation(s)
- F.R. Bertin
- Department of Veterinary Clinical Sciences; College of Veterinary Medicine; Purdue University; West Lafayette IN
| | - A. Reising
- Hagyard Equine Medical Institute; Lexington KY
| | - N.M. Slovis
- Hagyard Equine Medical Institute; Lexington KY
| | - P.D. Constable
- Department of Veterinary Clinical Sciences; College of Veterinary Medicine; Purdue University; West Lafayette IN
| | - S.D. Taylor
- Department of Veterinary Clinical Sciences; College of Veterinary Medicine; Purdue University; West Lafayette IN
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Vaughan JA, Tkach VV, Greiman SE. Neorickettsial endosymbionts of the digenea: diversity, transmission and distribution. ADVANCES IN PARASITOLOGY 2012; 79:253-97. [PMID: 22726644 DOI: 10.1016/b978-0-12-398457-9.00003-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Digeneans are endoparasitic flatworms with complex life cycles and distinct life stages that parasitize different host species. Some digenean species harbour bacterial endosymbionts known as Neorickettsia (Order Rickettsiales, Family Anaplasmataceae). Neorickettsia occur in all life stages and are maintained by vertical transmission. Far from benign however, Neorickettsia may also be transmitted horizontally by digenean parasites to their vertebrate definitive hosts. Once inside, Neorickettsia can infect macrophages and other cell types. In some vertebrate species (e.g. dogs, horses and humans), neorickettsial infections cause severe disease. Taken from a mostly parasitological perspective, this article summarizes our current knowledge on the transmission ecology of neorickettsiae, both for pathogenic species and for neorickettsiae of unknown pathogenicity. In addition, we discuss the diversity, phylogeny and geographical distribution of neorickettsiae, as well as their possible evolutionary associations with various groups of digeneans. Our understanding of neorickettsiae is at an early stage and there are undoubtedly many more neorickettsial endosymbioses with digeneans waiting to be discovered. Because neorickettsiae can infect vertebrates, it is particularly important to examine digenean species that regularly infect humans. Rapid advances in molecular tools and their application towards bacterial identification bode well for our future progress in understanding the biology of Neorickettsia.
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Gibson KE, Pastenkos G, Moesta S, Rikihisa Y. Neorickettsia risticii surface-exposed proteins: proteomics identification, recognition by naturally-infected horses, and strain variations. Vet Res 2011; 42:71. [PMID: 21635728 PMCID: PMC3127766 DOI: 10.1186/1297-9716-42-71] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 06/02/2011] [Indexed: 11/16/2022] Open
Abstract
Neorickettsia risticii is the Gram-negative, obligate, and intracellular bacterial pathogen responsible for Potomac horse fever (PHF): an important acute systemic disease of horses. N. risticii surface proteins, critical for immune recognition, have not been thoroughly characterized. In this paper, we identified the 51-kDa antigen (P51) as a major surface-exposed outer membrane protein of older and contemporary strains of N. risticii through mass spectrometry of streptavidin-purified biotinylated surface-labeled proteins. Western blot analysis of sera from naturally-infected horses demonstrated universal and strong recognition of recombinant P51 over other Neorickettsia recombinant proteins. Comparisons of amino acid sequences for predicted secondary structures of P51, as well as Neorickettsia surface proteins 2 (Nsp2) and 3 (Nsp3) among N. risticii strains from horses with PHF during a 26-year period throughout the United States revealed that the majority of variations among strains were concentrated in regions predicted to be external loops of their β-barrel structures. Large insertions or deletions occurred within a tandem-repeat region in Ssa3. These data demonstrate patterns of geographical association for P51 and temporal associations for Nsp2, Nsp3, and Ssa3, indicating evolutionary trends for these Neorickettsia surface antigen genes. This study showed N. risticii surface protein population dynamics, providing groundwork for designing immunodiagnostic targets for PHF.
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Affiliation(s)
- Kathryn E Gibson
- Department of Veterinary Biosciences, The Ohio State University College of Veterinary Medicine, 1925 Coffey Rd, Columbus, OH 43210, USA.
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Gibson KE, Rikihisa Y. Molecular link of different stages of the trematode host of Neorickettsia risticii to Acanthatrium oregonense. Environ Microbiol 2008; 10:2064-73. [PMID: 18422641 DOI: 10.1111/j.1462-2920.2008.01625.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neorickettsia risticii, the obligatory intracellular bacterium that causes Potomac horse fever, has been detected in various developmental stages of digenetic trematodes in the environment. Neorickettsia risticii-infected gravid trematodes were identified as Acanthatrium oregonense, based on morphologic keys. However, whether immature trematodes harbouring N. risticii are also A. oregonense was unknown. The objective of this study was to infer the life cycle of N. risticii-positive trematode hosts and transstadial transmission of the bacterium by molecularly characterizing the relationship among adult and immature stages of trematodes confirmed infected with N. risticii. Sequences of 18S ribosomal RNA genes up to 1922 bp in size were obtained from infected adult gravid trematodes, sporocysts and cercariae, and metacercariae. The sequences from the different immature stages of trematode are closely related to those of adult trematodes, some with 100% sequence identity; thus, they likely are life stages of A. oregonense. Comparisons with known 18S ribosomal RNA gene sequences of other digenetic trematodes indicated that all tested stages of the N. risticii-positive trematodes belong to the family Lecithodendriidae, supporting the morphological identification.
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Affiliation(s)
- Kathryn E Gibson
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
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Zheng Y, Luo X, Jing Z, Hu Z, Cai X. Comparison of 18S ribosomal RNA gene sequences of Eurytrema coelmaticum and Eurytrema pancreaticum. Parasitol Res 2006; 100:645-6. [PMID: 17004097 DOI: 10.1007/s00436-006-0281-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 07/06/2006] [Indexed: 11/25/2022]
Abstract
The partial 18S rRNA sequences of E. coelmaticum and E. pancreaticum were amplified using conserved primers and an evolutionary tree was constructed using Neighbor-Joining. The percent identity of Eurytrema species with other Dicrocoeliidae varied from 97.5 to 98.2, while the percent identity between the two Eurytrema species was up to 99.3. The tree showed that E. coelmaticum and E. pancreaticum were not situated in the same position, and they formed one cluster with L. collurioni. These results support a confirmation with molecular data that E. coelomaticum and E. pancreaticum are different species which apparently were not seriously questioned in the past.
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Affiliation(s)
- Yadong Zheng
- State Key Laboratory on Veterinary Etiological Biology and Gansu Provincial Key Laboratory of Veterinary Parasitology, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu 730046, China.
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Gibson KE, Rikihisa Y, Zhang C, Martin C. Neorickettsia risticii is vertically transmitted in the trematode Acanthatrium oregonense and horizontally transmitted to bats. Environ Microbiol 2005; 7:203-12. [PMID: 15658987 DOI: 10.1111/j.1462-2920.2004.00683.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Potomac horse fever is known to be transmitted through the ingestion of caddisflies parasitized with Neorickettsia (formerly Ehrlichia) risticii-infected metacercaria. However, the species of trematode involved and how N. risticii is maintained in nature are unknown. In this study, gravid trematodes were recovered from the intestines of 12 out of 15 Eptesicus fuscus big brown bats and eight out of nine Myotis lucifugus little brown bats from various sites in Pennsylvania, USA. Trematode specimens isolated from six E. fuscus bats contained N. risticii DNA. The trematode was identified as Acanthatrium oregonense. N. risticii was detected within individual trematode eggs by polymerase chain reaction as well as by immunofluorescence labelling with an anti-N. risticii antibody, indicating that N. risticii is vertically transmitted (from adult to egg) in A. oregonense. Furthermore, N. risticii DNA was detected in the blood, liver or spleen of 23 out of 53 E. fuscus and M. lucifugus bats, suggesting that N. risticii can also be transmitted horizontally from trematode to bat. These results indicate that A. oregonense is a natural reservoir and probably a vector of N. risticii.
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Affiliation(s)
- Kathryn E Gibson
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
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